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<pre><span class="sourceLineNo">001</span>/*<a name="line.1"></a>
<span class="sourceLineNo">002</span> * Licensed to the Apache Software Foundation (ASF) under one or more<a name="line.2"></a>
<span class="sourceLineNo">003</span> * contributor license agreements.  See the NOTICE file distributed with<a name="line.3"></a>
<span class="sourceLineNo">004</span> * this work for additional information regarding copyright ownership.<a name="line.4"></a>
<span class="sourceLineNo">005</span> * The ASF licenses this file to You under the Apache License, Version 2.0<a name="line.5"></a>
<span class="sourceLineNo">006</span> * (the "License"); you may not use this file except in compliance with<a name="line.6"></a>
<span class="sourceLineNo">007</span> * the License.  You may obtain a copy of the License at<a name="line.7"></a>
<span class="sourceLineNo">008</span> *<a name="line.8"></a>
<span class="sourceLineNo">009</span> *      http://www.apache.org/licenses/LICENSE-2.0<a name="line.9"></a>
<span class="sourceLineNo">010</span> *<a name="line.10"></a>
<span class="sourceLineNo">011</span> * Unless required by applicable law or agreed to in writing, software<a name="line.11"></a>
<span class="sourceLineNo">012</span> * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.12"></a>
<span class="sourceLineNo">013</span> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.13"></a>
<span class="sourceLineNo">014</span> * See the License for the specific language governing permissions and<a name="line.14"></a>
<span class="sourceLineNo">015</span> * limitations under the License.<a name="line.15"></a>
<span class="sourceLineNo">016</span> */<a name="line.16"></a>
<span class="sourceLineNo">017</span><a name="line.17"></a>
<span class="sourceLineNo">018</span>package org.apache.commons.logging;<a name="line.18"></a>
<span class="sourceLineNo">019</span><a name="line.19"></a>
<span class="sourceLineNo">020</span>import java.io.BufferedReader;<a name="line.20"></a>
<span class="sourceLineNo">021</span>import java.io.FileOutputStream;<a name="line.21"></a>
<span class="sourceLineNo">022</span>import java.io.IOException;<a name="line.22"></a>
<span class="sourceLineNo">023</span>import java.io.InputStream;<a name="line.23"></a>
<span class="sourceLineNo">024</span>import java.io.InputStreamReader;<a name="line.24"></a>
<span class="sourceLineNo">025</span>import java.io.PrintStream;<a name="line.25"></a>
<span class="sourceLineNo">026</span>import java.lang.reflect.InvocationTargetException;<a name="line.26"></a>
<span class="sourceLineNo">027</span>import java.lang.reflect.Method;<a name="line.27"></a>
<span class="sourceLineNo">028</span>import java.net.URL;<a name="line.28"></a>
<span class="sourceLineNo">029</span>import java.net.URLConnection;<a name="line.29"></a>
<span class="sourceLineNo">030</span>import java.security.AccessController;<a name="line.30"></a>
<span class="sourceLineNo">031</span>import java.security.PrivilegedAction;<a name="line.31"></a>
<span class="sourceLineNo">032</span>import java.util.Enumeration;<a name="line.32"></a>
<span class="sourceLineNo">033</span>import java.util.Hashtable;<a name="line.33"></a>
<span class="sourceLineNo">034</span>import java.util.Properties;<a name="line.34"></a>
<span class="sourceLineNo">035</span><a name="line.35"></a>
<span class="sourceLineNo">036</span>/**<a name="line.36"></a>
<span class="sourceLineNo">037</span> * Factory for creating {@link Log} instances, with discovery and<a name="line.37"></a>
<span class="sourceLineNo">038</span> * configuration features similar to that employed by standard Java APIs<a name="line.38"></a>
<span class="sourceLineNo">039</span> * such as JAXP.<a name="line.39"></a>
<span class="sourceLineNo">040</span> * &lt;p&gt;<a name="line.40"></a>
<span class="sourceLineNo">041</span> * &lt;strong&gt;IMPLEMENTATION NOTE&lt;/strong&gt; - This implementation is heavily<a name="line.41"></a>
<span class="sourceLineNo">042</span> * based on the SAXParserFactory and DocumentBuilderFactory implementations<a name="line.42"></a>
<span class="sourceLineNo">043</span> * (corresponding to the JAXP pluggability APIs) found in Apache Xerces.<a name="line.43"></a>
<span class="sourceLineNo">044</span> *<a name="line.44"></a>
<span class="sourceLineNo">045</span> * @version $Id: LogFactory.java 1449064 2013-02-22 14:49:22Z tn $<a name="line.45"></a>
<span class="sourceLineNo">046</span> */<a name="line.46"></a>
<span class="sourceLineNo">047</span>public abstract class LogFactory {<a name="line.47"></a>
<span class="sourceLineNo">048</span>    // Implementation note re AccessController usage<a name="line.48"></a>
<span class="sourceLineNo">049</span>    //<a name="line.49"></a>
<span class="sourceLineNo">050</span>    // It is important to keep code invoked via an AccessController to small<a name="line.50"></a>
<span class="sourceLineNo">051</span>    // auditable blocks. Such code must carefully evaluate all user input<a name="line.51"></a>
<span class="sourceLineNo">052</span>    // (parameters, system properties, config file contents, etc). As an<a name="line.52"></a>
<span class="sourceLineNo">053</span>    // example, a Log implementation should not write to its logfile<a name="line.53"></a>
<span class="sourceLineNo">054</span>    // with an AccessController anywhere in the call stack, otherwise an<a name="line.54"></a>
<span class="sourceLineNo">055</span>    // insecure application could configure the log implementation to write<a name="line.55"></a>
<span class="sourceLineNo">056</span>    // to a protected file using the privileges granted to JCL rather than<a name="line.56"></a>
<span class="sourceLineNo">057</span>    // to the calling application.<a name="line.57"></a>
<span class="sourceLineNo">058</span>    //<a name="line.58"></a>
<span class="sourceLineNo">059</span>    // Under no circumstance should a non-private method return data that is<a name="line.59"></a>
<span class="sourceLineNo">060</span>    // retrieved via an AccessController. That would allow an insecure app<a name="line.60"></a>
<span class="sourceLineNo">061</span>    // to invoke that method and obtain data that it is not permitted to have.<a name="line.61"></a>
<span class="sourceLineNo">062</span>    //<a name="line.62"></a>
<span class="sourceLineNo">063</span>    // Invoking user-supplied code with an AccessController set is not a major<a name="line.63"></a>
<span class="sourceLineNo">064</span>    // issue (eg invoking the constructor of the class specified by<a name="line.64"></a>
<span class="sourceLineNo">065</span>    // HASHTABLE_IMPLEMENTATION_PROPERTY). That class will be in a different<a name="line.65"></a>
<span class="sourceLineNo">066</span>    // trust domain, and therefore must have permissions to do whatever it<a name="line.66"></a>
<span class="sourceLineNo">067</span>    // is trying to do regardless of the permissions granted to JCL. There is<a name="line.67"></a>
<span class="sourceLineNo">068</span>    // a slight issue in that untrusted code may point that environment var<a name="line.68"></a>
<span class="sourceLineNo">069</span>    // to another trusted library, in which case the code runs if both that<a name="line.69"></a>
<span class="sourceLineNo">070</span>    // lib and JCL have the necessary permissions even when the untrusted<a name="line.70"></a>
<span class="sourceLineNo">071</span>    // caller does not. That's a pretty hard route to exploit though.<a name="line.71"></a>
<span class="sourceLineNo">072</span><a name="line.72"></a>
<span class="sourceLineNo">073</span>    // ----------------------------------------------------- Manifest Constants<a name="line.73"></a>
<span class="sourceLineNo">074</span><a name="line.74"></a>
<span class="sourceLineNo">075</span>    /**<a name="line.75"></a>
<span class="sourceLineNo">076</span>     * The name (&lt;code&gt;priority&lt;/code&gt;) of the key in the config file used to<a name="line.76"></a>
<span class="sourceLineNo">077</span>     * specify the priority of that particular config file. The associated value<a name="line.77"></a>
<span class="sourceLineNo">078</span>     * is a floating-point number; higher values take priority over lower values.<a name="line.78"></a>
<span class="sourceLineNo">079</span>     */<a name="line.79"></a>
<span class="sourceLineNo">080</span>    public static final String PRIORITY_KEY = "priority";<a name="line.80"></a>
<span class="sourceLineNo">081</span><a name="line.81"></a>
<span class="sourceLineNo">082</span>    /**<a name="line.82"></a>
<span class="sourceLineNo">083</span>     * The name (&lt;code&gt;use_tccl&lt;/code&gt;) of the key in the config file used<a name="line.83"></a>
<span class="sourceLineNo">084</span>     * to specify whether logging classes should be loaded via the thread<a name="line.84"></a>
<span class="sourceLineNo">085</span>     * context class loader (TCCL), or not. By default, the TCCL is used.<a name="line.85"></a>
<span class="sourceLineNo">086</span>     */<a name="line.86"></a>
<span class="sourceLineNo">087</span>    public static final String TCCL_KEY = "use_tccl";<a name="line.87"></a>
<span class="sourceLineNo">088</span><a name="line.88"></a>
<span class="sourceLineNo">089</span>    /**<a name="line.89"></a>
<span class="sourceLineNo">090</span>     * The name (&lt;code&gt;org.apache.commons.logging.LogFactory&lt;/code&gt;) of the property<a name="line.90"></a>
<span class="sourceLineNo">091</span>     * used to identify the LogFactory implementation<a name="line.91"></a>
<span class="sourceLineNo">092</span>     * class name. This can be used as a system property, or as an entry in a<a name="line.92"></a>
<span class="sourceLineNo">093</span>     * configuration properties file.<a name="line.93"></a>
<span class="sourceLineNo">094</span>     */<a name="line.94"></a>
<span class="sourceLineNo">095</span>    public static final String FACTORY_PROPERTY = "org.apache.commons.logging.LogFactory";<a name="line.95"></a>
<span class="sourceLineNo">096</span><a name="line.96"></a>
<span class="sourceLineNo">097</span>    /**<a name="line.97"></a>
<span class="sourceLineNo">098</span>     * The fully qualified class name of the fallback &lt;code&gt;LogFactory&lt;/code&gt;<a name="line.98"></a>
<span class="sourceLineNo">099</span>     * implementation class to use, if no other can be found.<a name="line.99"></a>
<span class="sourceLineNo">100</span>     */<a name="line.100"></a>
<span class="sourceLineNo">101</span>    public static final String FACTORY_DEFAULT = "org.apache.commons.logging.impl.LogFactoryImpl";<a name="line.101"></a>
<span class="sourceLineNo">102</span><a name="line.102"></a>
<span class="sourceLineNo">103</span>    /**<a name="line.103"></a>
<span class="sourceLineNo">104</span>     * The name (&lt;code&gt;commons-logging.properties&lt;/code&gt;) of the properties file to search for.<a name="line.104"></a>
<span class="sourceLineNo">105</span>     */<a name="line.105"></a>
<span class="sourceLineNo">106</span>    public static final String FACTORY_PROPERTIES = "commons-logging.properties";<a name="line.106"></a>
<span class="sourceLineNo">107</span><a name="line.107"></a>
<span class="sourceLineNo">108</span>    /**<a name="line.108"></a>
<span class="sourceLineNo">109</span>     * JDK1.3+ &lt;a href="http://java.sun.com/j2se/1.3/docs/guide/jar/jar.html#Service%20Provider"&gt;<a name="line.109"></a>
<span class="sourceLineNo">110</span>     * 'Service Provider' specification&lt;/a&gt;.<a name="line.110"></a>
<span class="sourceLineNo">111</span>     */<a name="line.111"></a>
<span class="sourceLineNo">112</span>    protected static final String SERVICE_ID =<a name="line.112"></a>
<span class="sourceLineNo">113</span>        "META-INF/services/org.apache.commons.logging.LogFactory";<a name="line.113"></a>
<span class="sourceLineNo">114</span><a name="line.114"></a>
<span class="sourceLineNo">115</span>    /**<a name="line.115"></a>
<span class="sourceLineNo">116</span>     * The name (&lt;code&gt;org.apache.commons.logging.diagnostics.dest&lt;/code&gt;)<a name="line.116"></a>
<span class="sourceLineNo">117</span>     * of the property used to enable internal commons-logging<a name="line.117"></a>
<span class="sourceLineNo">118</span>     * diagnostic output, in order to get information on what logging<a name="line.118"></a>
<span class="sourceLineNo">119</span>     * implementations are being discovered, what classloaders they<a name="line.119"></a>
<span class="sourceLineNo">120</span>     * are loaded through, etc.<a name="line.120"></a>
<span class="sourceLineNo">121</span>     * &lt;p&gt;<a name="line.121"></a>
<span class="sourceLineNo">122</span>     * If a system property of this name is set then the value is<a name="line.122"></a>
<span class="sourceLineNo">123</span>     * assumed to be the name of a file. The special strings<a name="line.123"></a>
<span class="sourceLineNo">124</span>     * STDOUT or STDERR (case-sensitive) indicate output to<a name="line.124"></a>
<span class="sourceLineNo">125</span>     * System.out and System.err respectively.<a name="line.125"></a>
<span class="sourceLineNo">126</span>     * &lt;p&gt;<a name="line.126"></a>
<span class="sourceLineNo">127</span>     * Diagnostic logging should be used only to debug problematic<a name="line.127"></a>
<span class="sourceLineNo">128</span>     * configurations and should not be set in normal production use.<a name="line.128"></a>
<span class="sourceLineNo">129</span>     */<a name="line.129"></a>
<span class="sourceLineNo">130</span>    public static final String DIAGNOSTICS_DEST_PROPERTY =<a name="line.130"></a>
<span class="sourceLineNo">131</span>        "org.apache.commons.logging.diagnostics.dest";<a name="line.131"></a>
<span class="sourceLineNo">132</span><a name="line.132"></a>
<span class="sourceLineNo">133</span>    /**<a name="line.133"></a>
<span class="sourceLineNo">134</span>     * When null (the usual case), no diagnostic output will be<a name="line.134"></a>
<span class="sourceLineNo">135</span>     * generated by LogFactory or LogFactoryImpl. When non-null,<a name="line.135"></a>
<span class="sourceLineNo">136</span>     * interesting events will be written to the specified object.<a name="line.136"></a>
<span class="sourceLineNo">137</span>     */<a name="line.137"></a>
<span class="sourceLineNo">138</span>    private static PrintStream diagnosticsStream = null;<a name="line.138"></a>
<span class="sourceLineNo">139</span><a name="line.139"></a>
<span class="sourceLineNo">140</span>    /**<a name="line.140"></a>
<span class="sourceLineNo">141</span>     * A string that gets prefixed to every message output by the<a name="line.141"></a>
<span class="sourceLineNo">142</span>     * logDiagnostic method, so that users can clearly see which<a name="line.142"></a>
<span class="sourceLineNo">143</span>     * LogFactory class is generating the output.<a name="line.143"></a>
<span class="sourceLineNo">144</span>     */<a name="line.144"></a>
<span class="sourceLineNo">145</span>    private static final String diagnosticPrefix;<a name="line.145"></a>
<span class="sourceLineNo">146</span><a name="line.146"></a>
<span class="sourceLineNo">147</span>    /**<a name="line.147"></a>
<span class="sourceLineNo">148</span>     * Setting this system property<a name="line.148"></a>
<span class="sourceLineNo">149</span>     * (&lt;code&gt;org.apache.commons.logging.LogFactory.HashtableImpl&lt;/code&gt;)<a name="line.149"></a>
<span class="sourceLineNo">150</span>     * value allows the &lt;code&gt;Hashtable&lt;/code&gt; used to store<a name="line.150"></a>
<span class="sourceLineNo">151</span>     * classloaders to be substituted by an alternative implementation.<a name="line.151"></a>
<span class="sourceLineNo">152</span>     * &lt;p&gt;<a name="line.152"></a>
<span class="sourceLineNo">153</span>     * &lt;strong&gt;Note:&lt;/strong&gt; &lt;code&gt;LogFactory&lt;/code&gt; will print:<a name="line.153"></a>
<span class="sourceLineNo">154</span>     * &lt;code&gt;&lt;pre&gt;<a name="line.154"></a>
<span class="sourceLineNo">155</span>     * [ERROR] LogFactory: Load of custom hashtable failed&lt;/em&gt;<a name="line.155"></a>
<span class="sourceLineNo">156</span>     * &lt;/pre&gt;&lt;/code&gt;<a name="line.156"></a>
<span class="sourceLineNo">157</span>     * to system error and then continue using a standard Hashtable.<a name="line.157"></a>
<span class="sourceLineNo">158</span>     * &lt;p&gt;<a name="line.158"></a>
<span class="sourceLineNo">159</span>     * &lt;strong&gt;Usage:&lt;/strong&gt; Set this property when Java is invoked<a name="line.159"></a>
<span class="sourceLineNo">160</span>     * and &lt;code&gt;LogFactory&lt;/code&gt; will attempt to load a new instance<a name="line.160"></a>
<span class="sourceLineNo">161</span>     * of the given implementation class.<a name="line.161"></a>
<span class="sourceLineNo">162</span>     * For example, running the following ant scriplet:<a name="line.162"></a>
<span class="sourceLineNo">163</span>     * &lt;code&gt;&lt;pre&gt;<a name="line.163"></a>
<span class="sourceLineNo">164</span>     *  &amp;lt;java classname="${test.runner}" fork="yes" failonerror="${test.failonerror}"&amp;gt;<a name="line.164"></a>
<span class="sourceLineNo">165</span>     *     ...<a name="line.165"></a>
<span class="sourceLineNo">166</span>     *     &amp;lt;sysproperty<a name="line.166"></a>
<span class="sourceLineNo">167</span>     *        key="org.apache.commons.logging.LogFactory.HashtableImpl"<a name="line.167"></a>
<span class="sourceLineNo">168</span>     *        value="org.apache.commons.logging.AltHashtable"/&amp;gt;<a name="line.168"></a>
<span class="sourceLineNo">169</span>     *  &amp;lt;/java&amp;gt;<a name="line.169"></a>
<span class="sourceLineNo">170</span>     * &lt;/pre&gt;&lt;/code&gt;<a name="line.170"></a>
<span class="sourceLineNo">171</span>     * will mean that &lt;code&gt;LogFactory&lt;/code&gt; will load an instance of<a name="line.171"></a>
<span class="sourceLineNo">172</span>     * &lt;code&gt;org.apache.commons.logging.AltHashtable&lt;/code&gt;.<a name="line.172"></a>
<span class="sourceLineNo">173</span>     * &lt;p&gt;<a name="line.173"></a>
<span class="sourceLineNo">174</span>     * A typical use case is to allow a custom<a name="line.174"></a>
<span class="sourceLineNo">175</span>     * Hashtable implementation using weak references to be substituted.<a name="line.175"></a>
<span class="sourceLineNo">176</span>     * This will allow classloaders to be garbage collected without<a name="line.176"></a>
<span class="sourceLineNo">177</span>     * the need to release them (on 1.3+ JVMs only, of course ;).<a name="line.177"></a>
<span class="sourceLineNo">178</span>     */<a name="line.178"></a>
<span class="sourceLineNo">179</span>    public static final String HASHTABLE_IMPLEMENTATION_PROPERTY =<a name="line.179"></a>
<span class="sourceLineNo">180</span>        "org.apache.commons.logging.LogFactory.HashtableImpl";<a name="line.180"></a>
<span class="sourceLineNo">181</span><a name="line.181"></a>
<span class="sourceLineNo">182</span>    /** Name used to load the weak hashtable implementation by names. */<a name="line.182"></a>
<span class="sourceLineNo">183</span>    private static final String WEAK_HASHTABLE_CLASSNAME =<a name="line.183"></a>
<span class="sourceLineNo">184</span>        "org.apache.commons.logging.impl.WeakHashtable";<a name="line.184"></a>
<span class="sourceLineNo">185</span><a name="line.185"></a>
<span class="sourceLineNo">186</span>    /**<a name="line.186"></a>
<span class="sourceLineNo">187</span>     * A reference to the classloader that loaded this class. This is the<a name="line.187"></a>
<span class="sourceLineNo">188</span>     * same as LogFactory.class.getClassLoader(). However computing this<a name="line.188"></a>
<span class="sourceLineNo">189</span>     * value isn't quite as simple as that, as we potentially need to use<a name="line.189"></a>
<span class="sourceLineNo">190</span>     * AccessControllers etc. It's more efficient to compute it once and<a name="line.190"></a>
<span class="sourceLineNo">191</span>     * cache it here.<a name="line.191"></a>
<span class="sourceLineNo">192</span>     */<a name="line.192"></a>
<span class="sourceLineNo">193</span>    private static final ClassLoader thisClassLoader;<a name="line.193"></a>
<span class="sourceLineNo">194</span><a name="line.194"></a>
<span class="sourceLineNo">195</span>    // ----------------------------------------------------------- Constructors<a name="line.195"></a>
<span class="sourceLineNo">196</span><a name="line.196"></a>
<span class="sourceLineNo">197</span>    /**<a name="line.197"></a>
<span class="sourceLineNo">198</span>     * Protected constructor that is not available for public use.<a name="line.198"></a>
<span class="sourceLineNo">199</span>     */<a name="line.199"></a>
<span class="sourceLineNo">200</span>    protected LogFactory() {<a name="line.200"></a>
<span class="sourceLineNo">201</span>    }<a name="line.201"></a>
<span class="sourceLineNo">202</span><a name="line.202"></a>
<span class="sourceLineNo">203</span>    // --------------------------------------------------------- Public Methods<a name="line.203"></a>
<span class="sourceLineNo">204</span><a name="line.204"></a>
<span class="sourceLineNo">205</span>    /**<a name="line.205"></a>
<span class="sourceLineNo">206</span>     * Return the configuration attribute with the specified name (if any),<a name="line.206"></a>
<span class="sourceLineNo">207</span>     * or &lt;code&gt;null&lt;/code&gt; if there is no such attribute.<a name="line.207"></a>
<span class="sourceLineNo">208</span>     *<a name="line.208"></a>
<span class="sourceLineNo">209</span>     * @param name Name of the attribute to return<a name="line.209"></a>
<span class="sourceLineNo">210</span>     */<a name="line.210"></a>
<span class="sourceLineNo">211</span>    public abstract Object getAttribute(String name);<a name="line.211"></a>
<span class="sourceLineNo">212</span><a name="line.212"></a>
<span class="sourceLineNo">213</span>    /**<a name="line.213"></a>
<span class="sourceLineNo">214</span>     * Return an array containing the names of all currently defined<a name="line.214"></a>
<span class="sourceLineNo">215</span>     * configuration attributes.  If there are no such attributes, a zero<a name="line.215"></a>
<span class="sourceLineNo">216</span>     * length array is returned.<a name="line.216"></a>
<span class="sourceLineNo">217</span>     */<a name="line.217"></a>
<span class="sourceLineNo">218</span>    public abstract String[] getAttributeNames();<a name="line.218"></a>
<span class="sourceLineNo">219</span><a name="line.219"></a>
<span class="sourceLineNo">220</span>    /**<a name="line.220"></a>
<span class="sourceLineNo">221</span>     * Convenience method to derive a name from the specified class and<a name="line.221"></a>
<span class="sourceLineNo">222</span>     * call &lt;code&gt;getInstance(String)&lt;/code&gt; with it.<a name="line.222"></a>
<span class="sourceLineNo">223</span>     *<a name="line.223"></a>
<span class="sourceLineNo">224</span>     * @param clazz Class for which a suitable Log name will be derived<a name="line.224"></a>
<span class="sourceLineNo">225</span>     * @throws LogConfigurationException if a suitable &lt;code&gt;Log&lt;/code&gt;<a name="line.225"></a>
<span class="sourceLineNo">226</span>     *  instance cannot be returned<a name="line.226"></a>
<span class="sourceLineNo">227</span>     */<a name="line.227"></a>
<span class="sourceLineNo">228</span>    public abstract Log getInstance(Class clazz)<a name="line.228"></a>
<span class="sourceLineNo">229</span>        throws LogConfigurationException;<a name="line.229"></a>
<span class="sourceLineNo">230</span><a name="line.230"></a>
<span class="sourceLineNo">231</span>    /**<a name="line.231"></a>
<span class="sourceLineNo">232</span>     * Construct (if necessary) and return a &lt;code&gt;Log&lt;/code&gt; instance,<a name="line.232"></a>
<span class="sourceLineNo">233</span>     * using the factory's current set of configuration attributes.<a name="line.233"></a>
<span class="sourceLineNo">234</span>     * &lt;p&gt;<a name="line.234"></a>
<span class="sourceLineNo">235</span>     * &lt;strong&gt;NOTE&lt;/strong&gt; - Depending upon the implementation of<a name="line.235"></a>
<span class="sourceLineNo">236</span>     * the &lt;code&gt;LogFactory&lt;/code&gt; you are using, the &lt;code&gt;Log&lt;/code&gt;<a name="line.236"></a>
<span class="sourceLineNo">237</span>     * instance you are returned may or may not be local to the current<a name="line.237"></a>
<span class="sourceLineNo">238</span>     * application, and may or may not be returned again on a subsequent<a name="line.238"></a>
<span class="sourceLineNo">239</span>     * call with the same name argument.<a name="line.239"></a>
<span class="sourceLineNo">240</span>     *<a name="line.240"></a>
<span class="sourceLineNo">241</span>     * @param name Logical name of the &lt;code&gt;Log&lt;/code&gt; instance to be<a name="line.241"></a>
<span class="sourceLineNo">242</span>     *  returned (the meaning of this name is only known to the underlying<a name="line.242"></a>
<span class="sourceLineNo">243</span>     *  logging implementation that is being wrapped)<a name="line.243"></a>
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<span class="sourceLineNo">249</span><a name="line.249"></a>
<span class="sourceLineNo">250</span>    /**<a name="line.250"></a>
<span class="sourceLineNo">251</span>     * Release any internal references to previously created {@link Log}<a name="line.251"></a>
<span class="sourceLineNo">252</span>     * instances returned by this factory.  This is useful in environments<a name="line.252"></a>
<span class="sourceLineNo">253</span>     * like servlet containers, which implement application reloading by<a name="line.253"></a>
<span class="sourceLineNo">254</span>     * throwing away a ClassLoader.  Dangling references to objects in that<a name="line.254"></a>
<span class="sourceLineNo">255</span>     * class loader would prevent garbage collection.<a name="line.255"></a>
<span class="sourceLineNo">256</span>     */<a name="line.256"></a>
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<span class="sourceLineNo">258</span><a name="line.258"></a>
<span class="sourceLineNo">259</span>    /**<a name="line.259"></a>
<span class="sourceLineNo">260</span>     * Remove any configuration attribute associated with the specified name.<a name="line.260"></a>
<span class="sourceLineNo">261</span>     * If there is no such attribute, no action is taken.<a name="line.261"></a>
<span class="sourceLineNo">262</span>     *<a name="line.262"></a>
<span class="sourceLineNo">263</span>     * @param name Name of the attribute to remove<a name="line.263"></a>
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<span class="sourceLineNo">268</span>     * Set the configuration attribute with the specified name.  Calling<a name="line.268"></a>
<span class="sourceLineNo">269</span>     * this with a &lt;code&gt;null&lt;/code&gt; value is equivalent to calling<a name="line.269"></a>
<span class="sourceLineNo">270</span>     * &lt;code&gt;removeAttribute(name)&lt;/code&gt;.<a name="line.270"></a>
<span class="sourceLineNo">271</span>     *<a name="line.271"></a>
<span class="sourceLineNo">272</span>     * @param name Name of the attribute to set<a name="line.272"></a>
<span class="sourceLineNo">273</span>     * @param value Value of the attribute to set, or &lt;code&gt;null&lt;/code&gt;<a name="line.273"></a>
<span class="sourceLineNo">274</span>     *  to remove any setting for this attribute<a name="line.274"></a>
<span class="sourceLineNo">275</span>     */<a name="line.275"></a>
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<span class="sourceLineNo">277</span><a name="line.277"></a>
<span class="sourceLineNo">278</span>    // ------------------------------------------------------- Static Variables<a name="line.278"></a>
<span class="sourceLineNo">279</span><a name="line.279"></a>
<span class="sourceLineNo">280</span>    /**<a name="line.280"></a>
<span class="sourceLineNo">281</span>     * The previously constructed &lt;code&gt;LogFactory&lt;/code&gt; instances, keyed by<a name="line.281"></a>
<span class="sourceLineNo">282</span>     * the &lt;code&gt;ClassLoader&lt;/code&gt; with which it was created.<a name="line.282"></a>
<span class="sourceLineNo">283</span>     */<a name="line.283"></a>
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<span class="sourceLineNo">285</span><a name="line.285"></a>
<span class="sourceLineNo">286</span>    /**<a name="line.286"></a>
<span class="sourceLineNo">287</span>     * Previously constructed &lt;code&gt;LogFactory&lt;/code&gt; instance as in the<a name="line.287"></a>
<span class="sourceLineNo">288</span>     * &lt;code&gt;factories&lt;/code&gt; map, but for the case where<a name="line.288"></a>
<span class="sourceLineNo">289</span>     * &lt;code&gt;getClassLoader&lt;/code&gt; returns &lt;code&gt;null&lt;/code&gt;.<a name="line.289"></a>
<span class="sourceLineNo">290</span>     * This can happen when:<a name="line.290"></a>
<span class="sourceLineNo">291</span>     * &lt;ul&gt;<a name="line.291"></a>
<span class="sourceLineNo">292</span>     * &lt;li&gt;using JDK1.1 and the calling code is loaded via the system<a name="line.292"></a>
<span class="sourceLineNo">293</span>     *  classloader (very common)&lt;/li&gt;<a name="line.293"></a>
<span class="sourceLineNo">294</span>     * &lt;li&gt;using JDK1.2+ and the calling code is loaded via the boot<a name="line.294"></a>
<span class="sourceLineNo">295</span>     *  classloader (only likely for embedded systems work).&lt;/li&gt;<a name="line.295"></a>
<span class="sourceLineNo">296</span>     * &lt;/ul&gt;<a name="line.296"></a>
<span class="sourceLineNo">297</span>     * Note that &lt;code&gt;factories&lt;/code&gt; is a &lt;i&gt;Hashtable&lt;/i&gt; (not a HashMap),<a name="line.297"></a>
<span class="sourceLineNo">298</span>     * and hashtables don't allow null as a key.<a name="line.298"></a>
<span class="sourceLineNo">299</span>     * @deprecated since 1.1.2<a name="line.299"></a>
<span class="sourceLineNo">300</span>     */<a name="line.300"></a>
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<span class="sourceLineNo">302</span><a name="line.302"></a>
<span class="sourceLineNo">303</span>    /**<a name="line.303"></a>
<span class="sourceLineNo">304</span>     * Create the hashtable which will be used to store a map of<a name="line.304"></a>
<span class="sourceLineNo">305</span>     * (context-classloader -&gt; logfactory-object). Version 1.2+ of Java<a name="line.305"></a>
<span class="sourceLineNo">306</span>     * supports "weak references", allowing a custom Hashtable class<a name="line.306"></a>
<span class="sourceLineNo">307</span>     * to be used which uses only weak references to its keys. Using weak<a name="line.307"></a>
<span class="sourceLineNo">308</span>     * references can fix memory leaks on webapp unload in some cases (though<a name="line.308"></a>
<span class="sourceLineNo">309</span>     * not all). Version 1.1 of Java does not support weak references, so we<a name="line.309"></a>
<span class="sourceLineNo">310</span>     * must dynamically determine which we are using. And just for fun, this<a name="line.310"></a>
<span class="sourceLineNo">311</span>     * code also supports the ability for a system property to specify an<a name="line.311"></a>
<span class="sourceLineNo">312</span>     * arbitrary Hashtable implementation name.<a name="line.312"></a>
<span class="sourceLineNo">313</span>     * &lt;p&gt;<a name="line.313"></a>
<span class="sourceLineNo">314</span>     * Note that the correct way to ensure no memory leaks occur is to ensure<a name="line.314"></a>
<span class="sourceLineNo">315</span>     * that LogFactory.release(contextClassLoader) is called whenever a<a name="line.315"></a>
<span class="sourceLineNo">316</span>     * webapp is undeployed.<a name="line.316"></a>
<span class="sourceLineNo">317</span>     */<a name="line.317"></a>
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<span class="sourceLineNo">324</span>            // Permissions don't allow this to be accessed. Default to the "modern"<a name="line.324"></a>
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<span class="sourceLineNo">337</span><a name="line.337"></a>
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<span class="sourceLineNo">345</span>                    // we *really* want this output, even if diagnostics weren't<a name="line.345"></a>
<span class="sourceLineNo">346</span>                    // explicitly enabled by the user.<a name="line.346"></a>
<span class="sourceLineNo">347</span>                    System.err.println("[ERROR] LogFactory: Load of custom hashtable failed");<a name="line.347"></a>
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<span class="sourceLineNo">352</span>            result = new Hashtable();<a name="line.352"></a>
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<span class="sourceLineNo">357</span>    // --------------------------------------------------------- Static Methods<a name="line.357"></a>
<span class="sourceLineNo">358</span><a name="line.358"></a>
<span class="sourceLineNo">359</span>    /** Utility method to safely trim a string. */<a name="line.359"></a>
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<span class="sourceLineNo">366</span><a name="line.366"></a>
<span class="sourceLineNo">367</span>    /**<a name="line.367"></a>
<span class="sourceLineNo">368</span>     * Checks whether the supplied Throwable is one that needs to be<a name="line.368"></a>
<span class="sourceLineNo">369</span>     * re-thrown and ignores all others.<a name="line.369"></a>
<span class="sourceLineNo">370</span>     *<a name="line.370"></a>
<span class="sourceLineNo">371</span>     * The following errors are re-thrown:<a name="line.371"></a>
<span class="sourceLineNo">372</span>     * &lt;ul&gt;<a name="line.372"></a>
<span class="sourceLineNo">373</span>     *   &lt;li&gt;ThreadDeath&lt;/li&gt;<a name="line.373"></a>
<span class="sourceLineNo">374</span>     *   &lt;li&gt;VirtualMachineError&lt;/li&gt;<a name="line.374"></a>
<span class="sourceLineNo">375</span>     * &lt;/ul&gt;<a name="line.375"></a>
<span class="sourceLineNo">376</span>     *<a name="line.376"></a>
<span class="sourceLineNo">377</span>     * @param t the Throwable to check<a name="line.377"></a>
<span class="sourceLineNo">378</span>     */<a name="line.378"></a>
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<span class="sourceLineNo">381</span>            throw (ThreadDeath) t;<a name="line.381"></a>
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<span class="sourceLineNo">383</span>        if (t instanceof VirtualMachineError) {<a name="line.383"></a>
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<span class="sourceLineNo">386</span>        // All other instances of Throwable will be silently ignored<a name="line.386"></a>
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<span class="sourceLineNo">388</span><a name="line.388"></a>
<span class="sourceLineNo">389</span>    /**<a name="line.389"></a>
<span class="sourceLineNo">390</span>     * Construct (if necessary) and return a &lt;code&gt;LogFactory&lt;/code&gt;<a name="line.390"></a>
<span class="sourceLineNo">391</span>     * instance, using the following ordered lookup procedure to determine<a name="line.391"></a>
<span class="sourceLineNo">392</span>     * the name of the implementation class to be loaded.<a name="line.392"></a>
<span class="sourceLineNo">393</span>     * &lt;p&gt;<a name="line.393"></a>
<span class="sourceLineNo">394</span>     * &lt;ul&gt;<a name="line.394"></a>
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<span class="sourceLineNo">396</span>     *     property.&lt;/li&gt;<a name="line.396"></a>
<span class="sourceLineNo">397</span>     * &lt;li&gt;The JDK 1.3 Service Discovery mechanism&lt;/li&gt;<a name="line.397"></a>
<span class="sourceLineNo">398</span>     * &lt;li&gt;Use the properties file &lt;code&gt;commons-logging.properties&lt;/code&gt;<a name="line.398"></a>
<span class="sourceLineNo">399</span>     *     file, if found in the class path of this class.  The configuration<a name="line.399"></a>
<span class="sourceLineNo">400</span>     *     file is in standard &lt;code&gt;java.util.Properties&lt;/code&gt; format and<a name="line.400"></a>
<span class="sourceLineNo">401</span>     *     contains the fully qualified name of the implementation class<a name="line.401"></a>
<span class="sourceLineNo">402</span>     *     with the key being the system property defined above.&lt;/li&gt;<a name="line.402"></a>
<span class="sourceLineNo">403</span>     * &lt;li&gt;Fall back to a default implementation class<a name="line.403"></a>
<span class="sourceLineNo">404</span>     *     (&lt;code&gt;org.apache.commons.logging.impl.LogFactoryImpl&lt;/code&gt;).&lt;/li&gt;<a name="line.404"></a>
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<span class="sourceLineNo">406</span>     * &lt;p&gt;<a name="line.406"></a>
<span class="sourceLineNo">407</span>     * &lt;em&gt;NOTE&lt;/em&gt; - If the properties file method of identifying the<a name="line.407"></a>
<span class="sourceLineNo">408</span>     * &lt;code&gt;LogFactory&lt;/code&gt; implementation class is utilized, all of the<a name="line.408"></a>
<span class="sourceLineNo">409</span>     * properties defined in this file will be set as configuration attributes<a name="line.409"></a>
<span class="sourceLineNo">410</span>     * on the corresponding &lt;code&gt;LogFactory&lt;/code&gt; instance.<a name="line.410"></a>
<span class="sourceLineNo">411</span>     * &lt;p&gt;<a name="line.411"></a>
<span class="sourceLineNo">412</span>     * &lt;em&gt;NOTE&lt;/em&gt; - In a multi-threaded environment it is possible<a name="line.412"></a>
<span class="sourceLineNo">413</span>     * that two different instances will be returned for the same<a name="line.413"></a>
<span class="sourceLineNo">414</span>     * classloader environment.<a name="line.414"></a>
<span class="sourceLineNo">415</span>     *<a name="line.415"></a>
<span class="sourceLineNo">416</span>     * @throws LogConfigurationException if the implementation class is not<a name="line.416"></a>
<span class="sourceLineNo">417</span>     *  available or cannot be instantiated.<a name="line.417"></a>
<span class="sourceLineNo">418</span>     */<a name="line.418"></a>
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<span class="sourceLineNo">424</span>            // This is an odd enough situation to report about. This<a name="line.424"></a>
<span class="sourceLineNo">425</span>            // output will be a nuisance on JDK1.1, as the system<a name="line.425"></a>
<span class="sourceLineNo">426</span>            // classloader is null in that environment.<a name="line.426"></a>
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<span class="sourceLineNo">428</span>                logDiagnostic("Context classloader is null.");<a name="line.428"></a>
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<span class="sourceLineNo">431</span><a name="line.431"></a>
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<span class="sourceLineNo">437</span><a name="line.437"></a>
<span class="sourceLineNo">438</span>        if (isDiagnosticsEnabled()) {<a name="line.438"></a>
<span class="sourceLineNo">439</span>            logDiagnostic(<a name="line.439"></a>
<span class="sourceLineNo">440</span>                    "[LOOKUP] LogFactory implementation requested for the first time for context classloader " +<a name="line.440"></a>
<span class="sourceLineNo">441</span>                    objectId(contextClassLoader));<a name="line.441"></a>
<span class="sourceLineNo">442</span>            logHierarchy("[LOOKUP] ", contextClassLoader);<a name="line.442"></a>
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<span class="sourceLineNo">445</span>        // Load properties file.<a name="line.445"></a>
<span class="sourceLineNo">446</span>        //<a name="line.446"></a>
<span class="sourceLineNo">447</span>        // If the properties file exists, then its contents are used as<a name="line.447"></a>
<span class="sourceLineNo">448</span>        // "attributes" on the LogFactory implementation class. One particular<a name="line.448"></a>
<span class="sourceLineNo">449</span>        // property may also control which LogFactory concrete subclass is<a name="line.449"></a>
<span class="sourceLineNo">450</span>        // used, but only if other discovery mechanisms fail..<a name="line.450"></a>
<span class="sourceLineNo">451</span>        //<a name="line.451"></a>
<span class="sourceLineNo">452</span>        // As the properties file (if it exists) will be used one way or<a name="line.452"></a>
<span class="sourceLineNo">453</span>        // another in the end we may as well look for it first.<a name="line.453"></a>
<span class="sourceLineNo">454</span><a name="line.454"></a>
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<span class="sourceLineNo">463</span>                // The Boolean.valueOf(useTCCLStr).booleanValue() formulation<a name="line.463"></a>
<span class="sourceLineNo">464</span>                // is required for Java 1.2 compatibility.<a name="line.464"></a>
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<span class="sourceLineNo">467</span>                    // LogFactory or Log classes, just use the class that loaded<a name="line.467"></a>
<span class="sourceLineNo">468</span>                    // this abstract class. When this class is deployed in a shared<a name="line.468"></a>
<span class="sourceLineNo">469</span>                    // classpath of a container, it means webapps cannot deploy their<a name="line.469"></a>
<span class="sourceLineNo">470</span>                    // own logging implementations. It also means that it is up to the<a name="line.470"></a>
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<span class="sourceLineNo">473</span>                    baseClassLoader = thisClassLoader;<a name="line.473"></a>
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<span class="sourceLineNo">481</span>            logDiagnostic("[LOOKUP] Looking for system property [" + FACTORY_PROPERTY +<a name="line.481"></a>
<span class="sourceLineNo">482</span>                          "] to define the LogFactory subclass to use...");<a name="line.482"></a>
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<span class="sourceLineNo">489</span>                    logDiagnostic("[LOOKUP] Creating an instance of LogFactory class '" + factoryClass +<a name="line.489"></a>
<span class="sourceLineNo">490</span>                                  "' as specified by system property " + FACTORY_PROPERTY);<a name="line.490"></a>
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<span class="sourceLineNo">492</span>                factory = newFactory(factoryClass, baseClassLoader, contextClassLoader);<a name="line.492"></a>
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<span class="sourceLineNo">495</span>                    logDiagnostic("[LOOKUP] No system property [" + FACTORY_PROPERTY + "] defined.");<a name="line.495"></a>
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<span class="sourceLineNo">500</span>                logDiagnostic("[LOOKUP] A security exception occurred while trying to create an" +<a name="line.500"></a>
<span class="sourceLineNo">501</span>                              " instance of the custom factory class" + ": [" + trim(e.getMessage()) +<a name="line.501"></a>
<span class="sourceLineNo">502</span>                              "]. Trying alternative implementations...");<a name="line.502"></a>
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<span class="sourceLineNo">504</span>            // ignore<a name="line.504"></a>
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<span class="sourceLineNo">513</span>                              " instance of the custom factory class" + ": [" +<a name="line.513"></a>
<span class="sourceLineNo">514</span>                              trim(e.getMessage()) +<a name="line.514"></a>
<span class="sourceLineNo">515</span>                              "] as specified by a system property.");<a name="line.515"></a>
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<span class="sourceLineNo">524</span>        // that implements the desired interface.<a name="line.524"></a>
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<span class="sourceLineNo">528</span>                logDiagnostic("[LOOKUP] Looking for a resource file of name [" + SERVICE_ID +<a name="line.528"></a>
<span class="sourceLineNo">529</span>                              "] to define the LogFactory subclass to use...");<a name="line.529"></a>
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<span class="sourceLineNo">535</span>                    // This code is needed by EBCDIC and other strange systems.<a name="line.535"></a>
<span class="sourceLineNo">536</span>                    // It's a fix for bugs reported in xerces<a name="line.536"></a>
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<span class="sourceLineNo">539</span>                        rd = new BufferedReader(new InputStreamReader(is, "UTF-8"));<a name="line.539"></a>
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<span class="sourceLineNo">544</span>                    String factoryClassName = rd.readLine();<a name="line.544"></a>
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<span class="sourceLineNo">549</span>                            logDiagnostic("[LOOKUP]  Creating an instance of LogFactory class " +<a name="line.549"></a>
<span class="sourceLineNo">550</span>                                          factoryClassName +<a name="line.550"></a>
<span class="sourceLineNo">551</span>                                          " as specified by file '" + SERVICE_ID +<a name="line.551"></a>
<span class="sourceLineNo">552</span>                                          "' which was present in the path of the context classloader.");<a name="line.552"></a>
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<span class="sourceLineNo">559</span>                        logDiagnostic("[LOOKUP] No resource file with name '" + SERVICE_ID + "' found.");<a name="line.559"></a>
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<span class="sourceLineNo">567</span>                    logDiagnostic(<a name="line.567"></a>
<span class="sourceLineNo">568</span>                        "[LOOKUP] A security exception occurred while trying to create an" +<a name="line.568"></a>
<span class="sourceLineNo">569</span>                        " instance of the custom factory class" +<a name="line.569"></a>
<span class="sourceLineNo">570</span>                        ": [" + trim(ex.getMessage()) +<a name="line.570"></a>
<span class="sourceLineNo">571</span>                        "]. Trying alternative implementations...");<a name="line.571"></a>
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<span class="sourceLineNo">573</span>                // ignore<a name="line.573"></a>
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<span class="sourceLineNo">576</span><a name="line.576"></a>
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<span class="sourceLineNo">582</span>                    logDiagnostic(<a name="line.582"></a>
<span class="sourceLineNo">583</span>                        "[LOOKUP] Looking in properties file for entry with key '" + FACTORY_PROPERTY +<a name="line.583"></a>
<span class="sourceLineNo">584</span>                        "' to define the LogFactory subclass to use...");<a name="line.584"></a>
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<span class="sourceLineNo">586</span>                String factoryClass = props.getProperty(FACTORY_PROPERTY);<a name="line.586"></a>
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<span class="sourceLineNo">589</span>                        logDiagnostic(<a name="line.589"></a>
<span class="sourceLineNo">590</span>                            "[LOOKUP] Properties file specifies LogFactory subclass '" + factoryClass + "'");<a name="line.590"></a>
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<span class="sourceLineNo">592</span>                    factory = newFactory(factoryClass, baseClassLoader, contextClassLoader);<a name="line.592"></a>
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<span class="sourceLineNo">594</span>                    // TODO: think about whether we need to handle exceptions from newFactory<a name="line.594"></a>
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<span class="sourceLineNo">596</span>                    if (isDiagnosticsEnabled()) {<a name="line.596"></a>
<span class="sourceLineNo">597</span>                        logDiagnostic("[LOOKUP] Properties file has no entry specifying LogFactory subclass.");<a name="line.597"></a>
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<span class="sourceLineNo">601</span>                if (isDiagnosticsEnabled()) {<a name="line.601"></a>
<span class="sourceLineNo">602</span>                    logDiagnostic("[LOOKUP] No properties file available to determine" + " LogFactory subclass from..");<a name="line.602"></a>
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<span class="sourceLineNo">607</span>        // Fourth, try the fallback implementation class<a name="line.607"></a>
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<span class="sourceLineNo">610</span>            if (isDiagnosticsEnabled()) {<a name="line.610"></a>
<span class="sourceLineNo">611</span>                logDiagnostic(<a name="line.611"></a>
<span class="sourceLineNo">612</span>                    "[LOOKUP] Loading the default LogFactory implementation '" + FACTORY_DEFAULT +<a name="line.612"></a>
<span class="sourceLineNo">613</span>                    "' via the same classloader that loaded this LogFactory" +<a name="line.613"></a>
<span class="sourceLineNo">614</span>                    " class (ie not looking in the context classloader).");<a name="line.614"></a>
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<span class="sourceLineNo">617</span>            // Note: unlike the above code which can try to load custom LogFactory<a name="line.617"></a>
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<span class="sourceLineNo">619</span>            // implementation via the context classloader because:<a name="line.619"></a>
<span class="sourceLineNo">620</span>            // * that can cause problems (see comments in newFactory method)<a name="line.620"></a>
<span class="sourceLineNo">621</span>            // * no-one should be customising the code of the default class<a name="line.621"></a>
<span class="sourceLineNo">622</span>            // Yes, we do give up the ability for the child to ship a newer<a name="line.622"></a>
<span class="sourceLineNo">623</span>            // version of the LogFactoryImpl class and have it used dynamically<a name="line.623"></a>
<span class="sourceLineNo">624</span>            // by an old LogFactory class in the parent, but that isn't<a name="line.624"></a>
<span class="sourceLineNo">625</span>            // necessarily a good idea anyway.<a name="line.625"></a>
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<span class="sourceLineNo">631</span>             * Always cache using context class loader.<a name="line.631"></a>
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<span class="sourceLineNo">649</span>     * Convenience method to return a named logger, without the application<a name="line.649"></a>
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<span class="sourceLineNo">651</span>     *<a name="line.651"></a>
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<span class="sourceLineNo">661</span>     * Convenience method to return a named logger, without the application<a name="line.661"></a>
<span class="sourceLineNo">662</span>     * having to care about factories.<a name="line.662"></a>
<span class="sourceLineNo">663</span>     *<a name="line.663"></a>
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<span class="sourceLineNo">679</span>     *<a name="line.679"></a>
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<span class="sourceLineNo">710</span>     * garbage collection.<a name="line.710"></a>
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<span class="sourceLineNo">758</span>     * a class even when forbidden to do so directly.<a name="line.758"></a>
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<span class="sourceLineNo">809</span>     *  attempting to get the context classloader.<a name="line.809"></a>
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<span class="sourceLineNo">857</span>                 * InvocationTargetException is thrown by 'invoke' when<a name="line.857"></a>
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<span class="sourceLineNo">953</span>     * (abstract) LogFactory.<a name="line.953"></a>
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<span class="sourceLineNo">955</span>     * &lt;h2&gt;ClassLoader conflicts&lt;/h2&gt;<a name="line.955"></a>
<span class="sourceLineNo">956</span>     * Note that there can be problems if the specified ClassLoader is not the<a name="line.956"></a>
<span class="sourceLineNo">957</span>     * same as the classloader that loaded this class, ie when loading a<a name="line.957"></a>
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<span class="sourceLineNo">959</span>     * &lt;p&gt;<a name="line.959"></a>
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<span class="sourceLineNo">967</span>     * the parent. When the code in this method finds some LogFactoryYYYY<a name="line.967"></a>
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<span class="sourceLineNo">969</span>     * LogFactory class defined in the child classloader, then LogFactoryYYYY<a name="line.969"></a>
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<span class="sourceLineNo">980</span>     * do not have to move the custom LogFactory subclass; that is ok as<a name="line.980"></a>
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<span class="sourceLineNo">997</span>        // Note that any unchecked exceptions thrown by the createFactory<a name="line.997"></a>
<span class="sourceLineNo">998</span>        // method will propagate out of this method; in particular a<a name="line.998"></a>
<span class="sourceLineNo">999</span>        // ClassCastException can be thrown.<a name="line.999"></a>
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<span class="sourceLineNo">1015</span>            logDiagnostic("Created object " + objectId(result) + " to manage classloader " +<a name="line.1015"></a>
<span class="sourceLineNo">1016</span>                          objectId(contextClassLoader));<a name="line.1016"></a>
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<span class="sourceLineNo">1018</span>        return (LogFactory)result;<a name="line.1018"></a>
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<span class="sourceLineNo">1021</span>    /**<a name="line.1021"></a>
<span class="sourceLineNo">1022</span>     * Method provided for backwards compatibility; see newFactory version that<a name="line.1022"></a>
<span class="sourceLineNo">1023</span>     * takes 3 parameters.<a name="line.1023"></a>
<span class="sourceLineNo">1024</span>     * &lt;p&gt;<a name="line.1024"></a>
<span class="sourceLineNo">1025</span>     * This method would only ever be called in some rather odd situation.<a name="line.1025"></a>
<span class="sourceLineNo">1026</span>     * Note that this method is static, so overriding in a subclass doesn't<a name="line.1026"></a>
<span class="sourceLineNo">1027</span>     * have any effect unless this method is called from a method in that<a name="line.1027"></a>
<span class="sourceLineNo">1028</span>     * subclass. However this method only makes sense to use from the<a name="line.1028"></a>
<span class="sourceLineNo">1029</span>     * getFactory method, and as that is almost always invoked via<a name="line.1029"></a>
<span class="sourceLineNo">1030</span>     * LogFactory.getFactory, any custom definition in a subclass would be<a name="line.1030"></a>
<span class="sourceLineNo">1031</span>     * pointless. Only a class with a custom getFactory method, then invoked<a name="line.1031"></a>
<span class="sourceLineNo">1032</span>     * directly via CustomFactoryImpl.getFactory or similar would ever call<a name="line.1032"></a>
<span class="sourceLineNo">1033</span>     * this. Anyway, it's here just in case, though the "managed class loader"<a name="line.1033"></a>
<span class="sourceLineNo">1034</span>     * value output to the diagnostics will not report the correct value.<a name="line.1034"></a>
<span class="sourceLineNo">1035</span>     */<a name="line.1035"></a>
<span class="sourceLineNo">1036</span>    protected static LogFactory newFactory(final String factoryClass,<a name="line.1036"></a>
<span class="sourceLineNo">1037</span>                                           final ClassLoader classLoader) {<a name="line.1037"></a>
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<span class="sourceLineNo">1041</span>    /**<a name="line.1041"></a>
<span class="sourceLineNo">1042</span>     * Implements the operations described in the javadoc for newFactory.<a name="line.1042"></a>
<span class="sourceLineNo">1043</span>     *<a name="line.1043"></a>
<span class="sourceLineNo">1044</span>     * @param factoryClass<a name="line.1044"></a>
<span class="sourceLineNo">1045</span>     * @param classLoader used to load the specified factory class. This is<a name="line.1045"></a>
<span class="sourceLineNo">1046</span>     *  expected to be either the TCCL or the classloader which loaded this<a name="line.1046"></a>
<span class="sourceLineNo">1047</span>     *  class. Note that the classloader which loaded this class might be<a name="line.1047"></a>
<span class="sourceLineNo">1048</span>     *  "null" (ie the bootloader) for embedded systems.<a name="line.1048"></a>
<span class="sourceLineNo">1049</span>     * @return either a LogFactory object or a LogConfigurationException object.<a name="line.1049"></a>
<span class="sourceLineNo">1050</span>     * @since 1.1<a name="line.1050"></a>
<span class="sourceLineNo">1051</span>     */<a name="line.1051"></a>
<span class="sourceLineNo">1052</span>    protected static Object createFactory(String factoryClass, ClassLoader classLoader) {<a name="line.1052"></a>
<span class="sourceLineNo">1053</span>        // This will be used to diagnose bad configurations<a name="line.1053"></a>
<span class="sourceLineNo">1054</span>        // and allow a useful message to be sent to the user<a name="line.1054"></a>
<span class="sourceLineNo">1055</span>        Class logFactoryClass = null;<a name="line.1055"></a>
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<span class="sourceLineNo">1058</span>                try {<a name="line.1058"></a>
<span class="sourceLineNo">1059</span>                    // First the given class loader param (thread class loader)<a name="line.1059"></a>
<span class="sourceLineNo">1060</span><a name="line.1060"></a>
<span class="sourceLineNo">1061</span>                    // Warning: must typecast here &amp; allow exception<a name="line.1061"></a>
<span class="sourceLineNo">1062</span>                    // to be generated/caught &amp; recast properly.<a name="line.1062"></a>
<span class="sourceLineNo">1063</span>                    logFactoryClass = classLoader.loadClass(factoryClass);<a name="line.1063"></a>
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<span class="sourceLineNo">1065</span>                        if (isDiagnosticsEnabled()) {<a name="line.1065"></a>
<span class="sourceLineNo">1066</span>                            logDiagnostic("Loaded class " + logFactoryClass.getName() +<a name="line.1066"></a>
<span class="sourceLineNo">1067</span>                                          " from classloader " + objectId(classLoader));<a name="line.1067"></a>
<span class="sourceLineNo">1068</span>                        }<a name="line.1068"></a>
<span class="sourceLineNo">1069</span>                    } else {<a name="line.1069"></a>
<span class="sourceLineNo">1070</span>                        //<a name="line.1070"></a>
<span class="sourceLineNo">1071</span>                        // This indicates a problem with the ClassLoader tree.<a name="line.1071"></a>
<span class="sourceLineNo">1072</span>                        // An incompatible ClassLoader was used to load the<a name="line.1072"></a>
<span class="sourceLineNo">1073</span>                        // implementation.<a name="line.1073"></a>
<span class="sourceLineNo">1074</span>                        // As the same classes<a name="line.1074"></a>
<span class="sourceLineNo">1075</span>                        // must be available in multiple class loaders,<a name="line.1075"></a>
<span class="sourceLineNo">1076</span>                        // it is very likely that multiple JCL jars are present.<a name="line.1076"></a>
<span class="sourceLineNo">1077</span>                        // The most likely fix for this<a name="line.1077"></a>
<span class="sourceLineNo">1078</span>                        // problem is to remove the extra JCL jars from the<a name="line.1078"></a>
<span class="sourceLineNo">1079</span>                        // ClassLoader hierarchy.<a name="line.1079"></a>
<span class="sourceLineNo">1080</span>                        //<a name="line.1080"></a>
<span class="sourceLineNo">1081</span>                        if (isDiagnosticsEnabled()) {<a name="line.1081"></a>
<span class="sourceLineNo">1082</span>                            logDiagnostic("Factory class " + logFactoryClass.getName() +<a name="line.1082"></a>
<span class="sourceLineNo">1083</span>                                          " loaded from classloader " + objectId(logFactoryClass.getClassLoader()) +<a name="line.1083"></a>
<span class="sourceLineNo">1084</span>                                          " does not extend '" + LogFactory.class.getName() +<a name="line.1084"></a>
<span class="sourceLineNo">1085</span>                                          "' as loaded by this classloader.");<a name="line.1085"></a>
<span class="sourceLineNo">1086</span>                            logHierarchy("[BAD CL TREE] ", classLoader);<a name="line.1086"></a>
<span class="sourceLineNo">1087</span>                        }<a name="line.1087"></a>
<span class="sourceLineNo">1088</span>                    }<a name="line.1088"></a>
<span class="sourceLineNo">1089</span><a name="line.1089"></a>
<span class="sourceLineNo">1090</span>                    return (LogFactory) logFactoryClass.newInstance();<a name="line.1090"></a>
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<span class="sourceLineNo">1092</span>                } catch (ClassNotFoundException ex) {<a name="line.1092"></a>
<span class="sourceLineNo">1093</span>                    if (classLoader == thisClassLoader) {<a name="line.1093"></a>
<span class="sourceLineNo">1094</span>                        // Nothing more to try, onwards.<a name="line.1094"></a>
<span class="sourceLineNo">1095</span>                        if (isDiagnosticsEnabled()) {<a name="line.1095"></a>
<span class="sourceLineNo">1096</span>                            logDiagnostic("Unable to locate any class called '" + factoryClass +<a name="line.1096"></a>
<span class="sourceLineNo">1097</span>                                          "' via classloader " + objectId(classLoader));<a name="line.1097"></a>
<span class="sourceLineNo">1098</span>                        }<a name="line.1098"></a>
<span class="sourceLineNo">1099</span>                        throw ex;<a name="line.1099"></a>
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<span class="sourceLineNo">1101</span>                    // ignore exception, continue<a name="line.1101"></a>
<span class="sourceLineNo">1102</span>                } catch (NoClassDefFoundError e) {<a name="line.1102"></a>
<span class="sourceLineNo">1103</span>                    if (classLoader == thisClassLoader) {<a name="line.1103"></a>
<span class="sourceLineNo">1104</span>                        // Nothing more to try, onwards.<a name="line.1104"></a>
<span class="sourceLineNo">1105</span>                        if (isDiagnosticsEnabled()) {<a name="line.1105"></a>
<span class="sourceLineNo">1106</span>                            logDiagnostic("Class '" + factoryClass + "' cannot be loaded" +<a name="line.1106"></a>
<span class="sourceLineNo">1107</span>                                          " via classloader " + objectId(classLoader) +<a name="line.1107"></a>
<span class="sourceLineNo">1108</span>                                          " - it depends on some other class that cannot be found.");<a name="line.1108"></a>
<span class="sourceLineNo">1109</span>                        }<a name="line.1109"></a>
<span class="sourceLineNo">1110</span>                        throw e;<a name="line.1110"></a>
<span class="sourceLineNo">1111</span>                    }<a name="line.1111"></a>
<span class="sourceLineNo">1112</span>                    // ignore exception, continue<a name="line.1112"></a>
<span class="sourceLineNo">1113</span>                } catch (ClassCastException e) {<a name="line.1113"></a>
<span class="sourceLineNo">1114</span>                    if (classLoader == thisClassLoader) {<a name="line.1114"></a>
<span class="sourceLineNo">1115</span>                        // There's no point in falling through to the code below that<a name="line.1115"></a>
<span class="sourceLineNo">1116</span>                        // tries again with thisClassLoader, because we've just tried<a name="line.1116"></a>
<span class="sourceLineNo">1117</span>                        // loading with that loader (not the TCCL). Just throw an<a name="line.1117"></a>
<span class="sourceLineNo">1118</span>                        // appropriate exception here.<a name="line.1118"></a>
<span class="sourceLineNo">1119</span><a name="line.1119"></a>
<span class="sourceLineNo">1120</span>                        final boolean implementsLogFactory = implementsLogFactory(logFactoryClass);<a name="line.1120"></a>
<span class="sourceLineNo">1121</span><a name="line.1121"></a>
<span class="sourceLineNo">1122</span>                        //<a name="line.1122"></a>
<span class="sourceLineNo">1123</span>                        // Construct a good message: users may not actual expect that a custom implementation<a name="line.1123"></a>
<span class="sourceLineNo">1124</span>                        // has been specified. Several well known containers use this mechanism to adapt JCL<a name="line.1124"></a>
<span class="sourceLineNo">1125</span>                        // to their native logging system.<a name="line.1125"></a>
<span class="sourceLineNo">1126</span>                        //<a name="line.1126"></a>
<span class="sourceLineNo">1127</span>                        final StringBuffer msg = new StringBuffer();<a name="line.1127"></a>
<span class="sourceLineNo">1128</span>                        msg.append("The application has specified that a custom LogFactory implementation ");<a name="line.1128"></a>
<span class="sourceLineNo">1129</span>                        msg.append("should be used but Class '");<a name="line.1129"></a>
<span class="sourceLineNo">1130</span>                        msg.append(factoryClass);<a name="line.1130"></a>
<span class="sourceLineNo">1131</span>                        msg.append("' cannot be converted to '");<a name="line.1131"></a>
<span class="sourceLineNo">1132</span>                        msg.append(LogFactory.class.getName());<a name="line.1132"></a>
<span class="sourceLineNo">1133</span>                        msg.append("'. ");<a name="line.1133"></a>
<span class="sourceLineNo">1134</span>                        if (implementsLogFactory) {<a name="line.1134"></a>
<span class="sourceLineNo">1135</span>                            msg.append("The conflict is caused by the presence of multiple LogFactory classes ");<a name="line.1135"></a>
<span class="sourceLineNo">1136</span>                            msg.append("in incompatible classloaders. ");<a name="line.1136"></a>
<span class="sourceLineNo">1137</span>                            msg.append("Background can be found in http://commons.apache.org/logging/tech.html. ");<a name="line.1137"></a>
<span class="sourceLineNo">1138</span>                            msg.append("If you have not explicitly specified a custom LogFactory then it is likely ");<a name="line.1138"></a>
<span class="sourceLineNo">1139</span>                            msg.append("that the container has set one without your knowledge. ");<a name="line.1139"></a>
<span class="sourceLineNo">1140</span>                            msg.append("In this case, consider using the commons-logging-adapters.jar file or ");<a name="line.1140"></a>
<span class="sourceLineNo">1141</span>                            msg.append("specifying the standard LogFactory from the command line. ");<a name="line.1141"></a>
<span class="sourceLineNo">1142</span>                        } else {<a name="line.1142"></a>
<span class="sourceLineNo">1143</span>                            msg.append("Please check the custom implementation. ");<a name="line.1143"></a>
<span class="sourceLineNo">1144</span>                        }<a name="line.1144"></a>
<span class="sourceLineNo">1145</span>                        msg.append("Help can be found @http://commons.apache.org/logging/troubleshooting.html.");<a name="line.1145"></a>
<span class="sourceLineNo">1146</span><a name="line.1146"></a>
<span class="sourceLineNo">1147</span>                        if (isDiagnosticsEnabled()) {<a name="line.1147"></a>
<span class="sourceLineNo">1148</span>                            logDiagnostic(msg.toString());<a name="line.1148"></a>
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<span class="sourceLineNo">1150</span><a name="line.1150"></a>
<span class="sourceLineNo">1151</span>                        throw new ClassCastException(msg.toString());<a name="line.1151"></a>
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<span class="sourceLineNo">1153</span><a name="line.1153"></a>
<span class="sourceLineNo">1154</span>                    // Ignore exception, continue. Presumably the classloader was the<a name="line.1154"></a>
<span class="sourceLineNo">1155</span>                    // TCCL; the code below will try to load the class via thisClassLoader.<a name="line.1155"></a>
<span class="sourceLineNo">1156</span>                    // This will handle the case where the original calling class is in<a name="line.1156"></a>
<span class="sourceLineNo">1157</span>                    // a shared classpath but the TCCL has a copy of LogFactory and the<a name="line.1157"></a>
<span class="sourceLineNo">1158</span>                    // specified LogFactory implementation; we will fall back to using the<a name="line.1158"></a>
<span class="sourceLineNo">1159</span>                    // LogFactory implementation from the same classloader as this class.<a name="line.1159"></a>
<span class="sourceLineNo">1160</span>                    //<a name="line.1160"></a>
<span class="sourceLineNo">1161</span>                    // Issue: this doesn't handle the reverse case, where this LogFactory<a name="line.1161"></a>
<span class="sourceLineNo">1162</span>                    // is in the webapp, and the specified LogFactory implementation is<a name="line.1162"></a>
<span class="sourceLineNo">1163</span>                    // in a shared classpath. In that case:<a name="line.1163"></a>
<span class="sourceLineNo">1164</span>                    // (a) the class really does implement LogFactory (bad log msg above)<a name="line.1164"></a>
<span class="sourceLineNo">1165</span>                    // (b) the fallback code will result in exactly the same problem.<a name="line.1165"></a>
<span class="sourceLineNo">1166</span>                }<a name="line.1166"></a>
<span class="sourceLineNo">1167</span>            }<a name="line.1167"></a>
<span class="sourceLineNo">1168</span><a name="line.1168"></a>
<span class="sourceLineNo">1169</span>            /* At this point, either classLoader == null, OR<a name="line.1169"></a>
<span class="sourceLineNo">1170</span>             * classLoader was unable to load factoryClass.<a name="line.1170"></a>
<span class="sourceLineNo">1171</span>             *<a name="line.1171"></a>
<span class="sourceLineNo">1172</span>             * In either case, we call Class.forName, which is equivalent<a name="line.1172"></a>
<span class="sourceLineNo">1173</span>             * to LogFactory.class.getClassLoader().load(name), ie we ignore<a name="line.1173"></a>
<span class="sourceLineNo">1174</span>             * the classloader parameter the caller passed, and fall back<a name="line.1174"></a>
<span class="sourceLineNo">1175</span>             * to trying the classloader associated with this class. See the<a name="line.1175"></a>
<span class="sourceLineNo">1176</span>             * javadoc for the newFactory method for more info on the<a name="line.1176"></a>
<span class="sourceLineNo">1177</span>             * consequences of this.<a name="line.1177"></a>
<span class="sourceLineNo">1178</span>             *<a name="line.1178"></a>
<span class="sourceLineNo">1179</span>             * Notes:<a name="line.1179"></a>
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<span class="sourceLineNo">1187</span>                              " - trying the classloader associated with this LogFactory.");<a name="line.1187"></a>
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<span class="sourceLineNo">1240</span>                // This will make it very hard to diagnose issues with JCL.<a name="line.1240"></a>
<span class="sourceLineNo">1241</span>                // Consider running less securely whilst debugging this issue.<a name="line.1241"></a>
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<span class="sourceLineNo">1243</span>                logDiagnostic("[CUSTOM LOG FACTORY] SecurityException thrown whilst trying to determine whether " +<a name="line.1243"></a>
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<span class="sourceLineNo">1262</span>                logDiagnostic("[CUSTOM LOG FACTORY] LogFactory class cannot be loaded by classloader which loaded " +<a name="line.1262"></a>
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<span class="sourceLineNo">1294</span>     * succeed when this jarfile is privileged but the caller is not.<a name="line.1294"></a>
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<span class="sourceLineNo">1343</span>                        // We must ensure that useCaches is set to false, as the<a name="line.1343"></a>
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<span class="sourceLineNo">1358</span>                            logDiagnostic("Unable to read URL " + url);<a name="line.1358"></a>
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<span class="sourceLineNo">1392</span>     * override logging settings in all webapps by placing a commons-logging.properties<a name="line.1392"></a>
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<span class="sourceLineNo">1677</span>     * its class.<a name="line.1677"></a>
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<span class="sourceLineNo">1701</span>    // stuff having been set up.<a name="line.1701"></a>
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<span class="sourceLineNo">1704</span>    // by any methods called from this block, as we want any static initialiser<a name="line.1704"></a>
<span class="sourceLineNo">1705</span>    // associated with the variable to run first. If static initialisers for<a name="line.1705"></a>
<span class="sourceLineNo">1706</span>    // variables run after this code, then (a) their value might be needed<a name="line.1706"></a>
<span class="sourceLineNo">1707</span>    // by methods called from here, and (b) they might *override* any value<a name="line.1707"></a>
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<span class="sourceLineNo">1709</span>    //<a name="line.1709"></a>
<span class="sourceLineNo">1710</span>    // So the wisest thing to do is just to place this code at the very end<a name="line.1710"></a>
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<span class="sourceLineNo">1712</span>    // ----------------------------------------------------------------------<a name="line.1712"></a>
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<span class="sourceLineNo">1714</span>    static {<a name="line.1714"></a>
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<span class="sourceLineNo">1719</span>        // being used via different classloaders within the same app, we<a name="line.1719"></a>
<span class="sourceLineNo">1720</span>        // ensure each logged message has a prefix of form<a name="line.1720"></a>
<span class="sourceLineNo">1721</span>        // [LogFactory from classloader OID]<a name="line.1721"></a>
<span class="sourceLineNo">1722</span>        //<a name="line.1722"></a>
<span class="sourceLineNo">1723</span>        // Note that this prefix should be kept consistent with that<a name="line.1723"></a>
<span class="sourceLineNo">1724</span>        // in LogFactoryImpl. However here we don't need to output info<a name="line.1724"></a>
<span class="sourceLineNo">1725</span>        // about the actual *instance* of LogFactory, as all methods that<a name="line.1725"></a>
<span class="sourceLineNo">1726</span>        // output diagnostics from this class are static.<a name="line.1726"></a>
<span class="sourceLineNo">1727</span>        String classLoaderName;<a name="line.1727"></a>
<span class="sourceLineNo">1728</span>        try {<a name="line.1728"></a>
<span class="sourceLineNo">1729</span>            ClassLoader classLoader = thisClassLoader;<a name="line.1729"></a>
<span class="sourceLineNo">1730</span>            if (thisClassLoader == null) {<a name="line.1730"></a>
<span class="sourceLineNo">1731</span>                classLoaderName = "BOOTLOADER";<a name="line.1731"></a>
<span class="sourceLineNo">1732</span>            } else {<a name="line.1732"></a>
<span class="sourceLineNo">1733</span>                classLoaderName = objectId(classLoader);<a name="line.1733"></a>
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<span class="sourceLineNo">1736</span>            classLoaderName = "UNKNOWN";<a name="line.1736"></a>
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<span class="sourceLineNo">1738</span>        diagnosticPrefix = "[LogFactory from " + classLoaderName + "] ";<a name="line.1738"></a>
<span class="sourceLineNo">1739</span>        diagnosticsStream = initDiagnostics();<a name="line.1739"></a>
<span class="sourceLineNo">1740</span>        logClassLoaderEnvironment(LogFactory.class);<a name="line.1740"></a>
<span class="sourceLineNo">1741</span>        factories = createFactoryStore();<a name="line.1741"></a>
<span class="sourceLineNo">1742</span>        if (isDiagnosticsEnabled()) {<a name="line.1742"></a>
<span class="sourceLineNo">1743</span>            logDiagnostic("BOOTSTRAP COMPLETED");<a name="line.1743"></a>
<span class="sourceLineNo">1744</span>        }<a name="line.1744"></a>
<span class="sourceLineNo">1745</span>    }<a name="line.1745"></a>
<span class="sourceLineNo">1746</span>}<a name="line.1746"></a>




























































</pre>
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